When you want to protect your horse in hot or humid conditions, UltraShield® sport sweat-resistant fly spray works as hard as you and your equine partner. Provides sweat-resistant protection for heavy workouts in the hottest, most humid weather. Repels and kills mosquitoes that may transmit West Nile virus. Protects against biting and nuisance flies and gnats. Water-based formula won't attract dust. Long-lasting repellency that protects and stays active for up to 14 days, even after rain. Sweat-resistant fly spray for humid weather.